Brake press die system, structure and processes

ABSTRACT

Structures are provided each having a high modulus of resilience as well as improved metallurgical gradients and physical characteristics and resulting sufficient resilience to avoid damage by impact stresses, while sufficiently hard and mechanically stable to maintain their dimensional stability.

United States Patent Cree, Jr. 1 Nov. 21, 1972 [54] BRAKE PRESS DIESYSTEM, 3,007,508 11/1961 Giordano ..72/386 STRUCTURE AND PROCESSES3,214,955 11/1965 Voth ..72/389 3,342,060 9/1967 Peterson ....72/470[72] g 'ggg ff g $56 3,610,019 10/1971 Denninger ..72/386 [22] Filed:June 24, 1971 Primary Examiner-Richard J. Herbst Assistant ExaminerGeneP. Crosby [21] 156360 AttorneyEly Silverman [52] US. Cl ..72/389, 72/475[57] ABSTRACT [51] Int. Cl. .3211! 37/10 s tructures are provlded eachhavmg a high modulus of [58] Flew of Search 352 resilience as well asimproved metallurgical gradients and physical characteristics andresulting sufficient resilience to avoid damage by impact stresses,while [56] References cued sufi'iciently hard and mechanically stable tomaintain UNITED STATES PATENTS their dimensional stability. 435,9869/1890 Tucker ...72/475 10 Claims, 13 Drawing Figures PATENTEDnum m2703,09

sum 1 or 3 INVENTOR.

34.. 34.2 659565 B. CREE JR ATTORNEY PATENTEDHOYZI 19R 3.703094 SHEET 3[IF 3 F /G. 8 F /G. 9

INVENTOR.

ATTORNEY BRAKE PRESS DIE SYSTEM, STRUCTURE AND PROCESSES BACKGROUND OFTHE INVENTION 1. Field of the Invention The field of invention to whichthis invention pertains are metalworking wherein an iron containingsheet is adjacent an aluminum containing component. metal deforming, andmetallurgical apparatus for treating solid metal.

2. Description of the Prior Art In the use of dies during brake pressoperation the male or punch dies are subjected to repeated compressiveimpact stresses while the female or bed dies are subjected to repeatedcompressive and bending impact stresses that are applied rapidly to andby the work against which such dies are used. Such impact stresses reachhigh values and, as is well known, cause fatigue failures of the dies.

Certain minimum hardness of die 'materials is required to preventexcessive wear yet conventional materials used for dies and having suchdegree of hardness have only limited fatigue strength.

Soft materials, as rubber used in rubber pad forming, wear too rapidlyto be economical and do not produce sharp comers or bends adequately andconsistently. Another approach to metal forming has been high speedforming. However, such rapid speed operation provides heat effects onthe worked parts and such high. speed treatment work hardens and makesbrittle the treated sheet.

SUMMARY OF THE INVENTION Multi-component aluminum alloy dies of highmodulus of resilience are provided with a hard pellicles. The dies areresilient throughout their interior mass although the points of contactare made particularly hard and the zones of high tensile stressparticularly strong. Accordingly, such dies are able to deformelastically during an impacting (press brake) operation so as togradually, considering the speed of changes involved in a metal workingstroke, apply force and absorb force and avoid absorption of mechanicalenergy over only very small die areas and volumes which absorption mightcreate localized generation of extreme heat, crystallization effects andgrain structure changes as might change the structure and mechanicalaction of such alloy dies. The metallurgical compositions areparticularly treated to provide such structure and operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a transversesection of a male brake press punch die according to this invention.

FIG. 2 is a side view of a transverse section of another brake presspunch die according to this invention.

FIG. 3 is a side view of a transverse section of a female brake pressdie according to this invention.

FIG. 4 is an overall view of mechanical press brake in which the punchesand dies of FIGS. 1-3 are used.

FIG. 5 is a curve of tensile strength relative to rate of cooling ofalloy materials used in apparatuses of FIGS. 1, 2 and 3.

FIG. 6 is a graph of effect of thickness and quenching media on averagecooling rates at midplane of alloy material of apparatuses of FIGS. 1-3.

FIG. 7 is a graph of tensile strength vs. hardness of alloy material ofapparatuses of FIGS. 1-3.

FIGS. 8 and 9 show a sequence of steps in a brake press operation usingthe dies of FIGS. 1 and 3, as end VIQWS.

FIG. 10 is a diagrammatic showing of the shoulder zone 10A of FIG. 9during a sequence of steps as in FIGS. 8 and 9.

FIG. 11 is an extrusion die according to this invention.

FIG. 12 is a hammer head according to this invention.

FIG. 13 illustrates a combination of piston rod and piston according tothis invention.

FIGS. 1 and 5 are shown partially in perspective. The plan views ofFIGS. 2 and 3 are to scale.

DEFINITIONS Brake press forming is a process in which the working pieceis placed over an open die and is pressed down into the die by a punchthat is actuated by the ram portion of a machine called a brake.

As to directionality:

Longitudinal means parallel to major dimension of direction of workingof section.

Long transverse" means to direction of working in parallel to width ofsection.

Short transverse means 90 to direction of working and parallel tothickness or minimum dimension of section.

Transverse" means 90 to direction of product having axial symmetry.

Rockwell hardness:

A diamond cone penetrator (l20) with a slightly rounded tip (radius 0.2mm) is loaded with a minor load of 10 kg., primarily to seat thepenetrator; a major load (regularly 150 kg. for C scale) is applied andreleased after a specific time, usually 10 sec. The hardness is measuredby the difference in depth of the major and minor loads.

Brinell Hardness number conversion: For Rockwell numbers C20 to 40:

Brinell hardness number 1,420,000/( Rockwell C number) 2 For Rockwellnumbers greater than C 40:

Brinell hardness number 25,000 I I00 Rockwell C Number (21) DESCRIPTIONOF THE PREFERRED EMBODIMENTS TABLE I working in Tensile strength p.s.i.Yield strength p.s.i. Elongatioufb in 2 in.

SL000 $8,000 71,000 -7B.000 l0 Shear strength p.|.i 49,000 -52,000

Modulus of elasticity 10.4 X lbsJin.

Surface hardness (500 kg. load 160 Brinell 10 MM Bali) Thermalconductivity Component I: by Weight Range Mn .30 Si .40 Fe .50 Cu 2.01.6-2.4 Mg 2.7 2.4-3.1 Cr .30 -.35 Zn 6.8 6.3-7.3 Al .szma uqst.

While the extrusion provides that each section, as shown in FIGS. 1, 2and 3, transverse to the length of the die as 11, 21 and 31,respectively, (which direction of length, as 81 (FIG. 1), is thedirection of extrusion) has similar mechanical properties along thelength of the die, these alloy extrudates are heat treated after forminginto shapes as shown in FIGS. 1, 2 and 3 and are not, accordingly, intheir final form homogeneous in all characteristics throughout all partsof each such sections along the long transverse direction thereof as 82in FIG. 1 or along their short transverse direction as 83, and havephysical and microstructure characteristics that vary as hereinbelowdescribed. The alloy extrudates in final form, although composedprimarily of aluminum are composed also of zinc, magnesium and copperinsolid solution and/or precipitated in such finely divided form as tobe substantially invisible up to about 100 X power although somemagnesium silicide (mg, Si) is visible.

These extrusions are made with sufficiently rounded corners to avoiddevelopment of cracks in the anodized coating although such coatings areporous, as shown by electron microphotograph. V

The extruded surfaces, as 18.1 and 18.2 and 28.1 and 28.2 and 37.3, 38.2and 38.1; i.e., are not even wrinkled, as seen under SOXX magnificationand free of Luder lines.

The straight punch, 11, is composed of an elongated straight punch bodyportion 12, punch cross 13, punch tail 14 and punch head operativelycombined into an integral unit. The head 15 has a wide shoulder portion16 and terminates in a punch nose 17.

FIG. 1 is the outline of one of a group of such dies; dimensions ofother dies of generally the same configuration are set out in TABLE III.The tail portion 14 has an upper left edge 14.1 and an upper right edge14.2, a

lower left edge 14.3 and a lower right edge 14.4 with a between edges13.1 and 13.3 and a right cross face I between edge 13.2 and 13.4.

The punch shaft portion 12 has a left. upper edge at corner 12.1, and aright upper edge at corner 12.2, a left lower edge at corner 12.3, and aright lower edge at corner 12.4, and a left shaft face, 12.5, betweencorners 12.1 and 12.3, and a right shaft face, 12.6, between corners12.2 and 12.4.

The punch head 15 has a wide shoulder 16 with an upper left edge 16.1and a lower left edge 16.3 and an upper right edge 16.2 and a lowerright edge 16.4, and a left shoulder face between edges 16.1 and 16.3and a right shoulder face between edges 16.1 and 16.3 and a rightshoulder face between edges 16.2 and 16.4. p

The punch nose 17 is located below the punch shoulder and spaced fromthe edges 16.3 and 16.4 by lefl punch face 18.1 and right punch face18.2 and has a small but definite radius of curvature.

The gooseneck punch, 31, is composed of an elongated gooseneck bodyportion 22, gooseneck cross 23, gooseneck tail 24 and gocseneck head 25operatively combined into an integral unit. The gooseneck head 25 has awide shoulder portion 26 and terminates in a nose 27.

FIG. 2 is the outline of one of a group of such dies; dimensions of adie of such configuration are set out in TABLE IV. The tail portion 24has an upper left edge 24.1 and an upper right edge 24.2, a lower leftedge 24.3 and a lower right edge 24.4 with a top tail face between edges24.1 and 24.2 and a left tail face between edges 24.1 and 24.3 and aright tail face between edges 24.2 and 24.4.

The gooseneck cross portion 23 has an upper left edge 23.1 and an upperright edge 23.2, a lower left edge 23.3 and a lower right corner 22.2,and a right middle edge 23.6, with a left shoulder face between edges23.1 and 23.3 and an upper right face between edges 23.2 and 23.6 and aright lower shoulder face between edges 23.6 and 22.2.

The gooseneck shaft portion 22 has a left upper edge at corner 22.2, anda right upper edge at corner 22.2, a left lower edge at corner 22.3 anda left lower edge at rounded corner 22.4, and a left shaft face, 22.5,between comers 22.1 and 22.3, and a right shaft face 22.6 betweencorners 22.2 and 22.4.

The gooseneck nose 27 is located below the shoulder 26 and spaced fromthe edges 26.3 and 22.4 by left gooseneck punch face 28.1 and lowerright gooseneck punch face 28.2 and an upper right gooseneck punch face28.3. The nose 27 has a definite but small radius of curvature.

The .bed or base or female die 31 is composed of a vertical straight diebody portion 32, die tail 34 and die head 35 operatively combined intoan integral unit. The die head 35 has a left shoulder 36 and a rightshoulder 37 on either side of a die groove 38.

P16. 3 is the outline of one of a group of such dies; dimensions of twosuch dies according to this invention are set out in TABLE V.

The tail portion 34. has an upper left edge 34.1 and an upper right edge34.2, a lower left edge 34.3 and a lower right edge 34.4, with a bottomtail face between edges 34.2 and 34.4 and a left tail face between edges34.1 and 34.3 and a right tail face between edges 34.2 and 34.4.

The body portion 32 has a lower left edge 32.1, and a lower rightedge32.2, with a left body face between edges 32.1 and 36.1 and a right bodyface between edges 32.2 and 37.2.

The die head 35 has a left shoulder 36 with an upper left edge 36.1 andan upper right edge 36.2 and a flat upper left shoulder face betweenedges 36.1 and 36.2.

The die head 35 has a right shoulder 37 with an upper right groove face38.2; faces 38.1 and 38.2 join a curved groove apex 39 at the bottom ofgroove 38 and join edges 36.2 and 37.1 at their tops.

The hardness of different points on the exterior surfaces and transversesections of such dies as illustrated IN FIGS. 1-3 were tested withresults as at TABLE II. Generally, in the dies so formed the greatesthardness is at the nose*, and the exterior surfaces other than at thenose are softer than at the nose and the core is even softer than thesurfaces other than at the nose. (*Edges 37.1 and 36.2 would be nose ofunit 31).

The high thermal conductivity of the aluminum alloy (about 1500B.T.U./hr./sq. ft./F./inch at 400 F. (while steel is only 300T.T.U./hr./sq. ft./F./inch) provides that, while heat transfer duringquenching is generally limited by resistance at the surface in contactwith the quenching medium a substantial thickness of the die body of thealloy as 7178-T-6 is, by quenching, brought to sufficiently high tensilestrength and hardness to provide the high modulus of resilience desiredas shown in the particular examples herein. For creation of similarproperties in other die shapes, the relation of tensile strength tohardness for the aluminum alloy used is set out in FIG. hereof so thatthe desired tensile strength may be determined and checked conveniently.Also, the relation of quench rate to strength is set out in FIG. 5hereof for two different alloys, 71 7;T- and 7075, so that the quenchrate for different portions of the die may be chosen to provide thedesired hardness of different portions thereof; e.g., at the nose andother outer surfaces of the dies made as herein described. The quenchrate used is achieved by the cooling rate shown in FIG. 6 hereof.

The dies, as 11, 21 and 31, each have a fibrous external surface layerof large recrystallized grains, which constituent particles areelongated in direction parallel to extrusion direction, (as 81 in FIG.1)while the center of each such extruded mass sufiers minimumdeformation. In the extrusion process, while there is somerecrystallization, the 7178 alloy used, like other of al. Zn-Mg-Cualloys of the 7xxx series show the least recrystallization and develophigh mechanical properties in the major portion of the extruded crosssection.

In such heat treated structure where the structure is primarilyunrecrystallized, tensile properties in the transverse direction, as 82and 83, are significantly lower than longitudinal properties alongdirection 81. Thus, the tensile strength is reduced in transversedirections 82 and 83 relative to longitudinal strength.

Anodic protection and surface hardening is provided to apparatus asshown in FIGS. 1-3 by treating the extruded and quenched die by thefollowing procedure.

The anodizing treatment uses 8-25 percent sulfuric acid with a peatadditive, at 2535 F., at current density of 24-36 amperes per squarefoot in stepped voltage increments with 20 volts D.C. starting steppedup to 90 volts at rate of 1 volt per minute; the oxide formation rate is30 minutes per mil thickness, in conventional manner (as taught at pages653 to 656 of Aluminum: Fabrication and Finishing, Volume 3 under HardAnodic Coatings) The results of the anodizing treatment are tested bystandard procedures as ASTM B110, ASTM B136, ASTM B133 and ASTM B244.

While these anodized surfaces are hard, their thickness is only a few lto 5) thousandths of an inch and, as viewed under the electronmicroscope, porous. Accordingly, the anodic coating does not interferewith the mechanical yieldability of the die material below andsupporting such coating and consequent high modulus of resilience andability to absorb impact energy the anodic coating thus is not separatedfrom its mechanical support and so provides continued electrolyticprotection thereto, and, thereby, corrosion resistance, notwithstandingthe stresses applied to such dies during normal usage thereof.

This anodic cladding provides electrochemical protection for the core atexposed edges and abraded or corroded areas.

The modulus of resilience is defined as Sf/ZE where S is the elasticlimit. The modulus of elasticity of the alloy 7178-T-6 used in elements11, 21 and 31 is only slightly lowered by the magnesium zinc, silicon,and copper added to pure aluminum and is about 10.4 X 10 psi. Thus, theability of the material of the apparatus 11, 21 and 31 to absorb impactis several times higher than would be provided by such shapes formed ofsteel of a comparable Brinell number. Steels which exhibit comparableBrinell numbers have, for steel, a tensile strength of 75,000 to 90,000pounds per square inch, so that on this basis the modulus of resilienceof apparatuses 11, 21 and 31 are between seven and nine times that ofsteel of comparable Brinell number.

Because of the excellent thermal conductivity of aluminum alloys as usedin the apparatuses as shown in FIGS. 1-3, the stroke by the nose of thedie, notwithstanding the creation of any localized temperature effectsthrough the mass of such dies (as 11 and 31). However, the thermalconductivity of this alloy material is especially effective inpermitting, also, even and deep cooling rates whereby the nose of thepunch and zone below the groove 38 and apex 39 of the die 31 areparticularly rapidly cooled and hardened, while the body of the die isnot, and the distribution of hardness as described for apparatus ofFIGS. 1-3 is achieved.

In brake press operations with the dies of this invention, the punch ormale die, as 11, is firmly placed in clamp 61 of the movable ram 66 ofconventional brake press and the female or base die as 31 is placed inthe lower jaw or bed 62 of the press, 60; then the work piece as 41 isplaced in the maw or opening 65 over the groove as 38 and supported onand in contact with the base die shoulders 36 and 37; the drive motor64, through clutch 71, flywheel as 72 and gears as 73 drives the upperpunch die downward relative to brake press housing 74 toward the apex 39of the groove 38 in the lower base or female die 31. Adjustment of theheight of the ram is made by a ram adjusting motor as 76 and adjustmentscrews as 77.

After the tools have been thus set up and the sheet height adjusted, thepress brake is cycled and the to-beworked metal as sheet 41 is bent tothe desired angle around the nose radius of the punch used. The distancethe ram punch (male die) as 11 travels into the bed die (female die) 31determines the bend angle of the work piece; such distance of entry bythe punch is determined by the shut height of the brake press machineand the span width or width of the die opening.

The span width of the female die, as 31; i.e., the distance between thetop surfaces of base shoulders 36 and 37 (between edges 36.2 and 37.1)and thickness of the work piece determine the force needed to bend thework piece 41. The mechanical wear of the dies determines the constancyof angle formed.

The width of each of the male dies or punches, 11 and 21, is far greaterthan any portion thereof; i.e., nose 17 and 27, that contacts the workpiece: only the nose forcefully contacts the work piece; the remainderof the width of the male die or punch (along'direction 83 of FIG. 1)primarily provides for rigidity and convenient and reliable positioningand such punch die body has a compressive yield strength far in excessof impact stresses applied thereto: the large volume and transversecross-section thereof and ability to yield permits a distribution of thecompressive stresses applied thereto relatively evenly throughout themass between the nose and the shoulder and, in combination with the highthermal conductivity of the mass, avoids any metallurgical changes dueto the temporary stresses met, as in 31, also.

The female portion of the die, as in FIG. 3, is hard surfaced atsurfaces 38.1, 38.2, and along curved edges 37.1 and 36.2. The portionsof the die that successively contacts the work are diagrammaticallyillustrated in FIGS. 8, 9 and as there illustrated, as the work piece 41is bent by the male die 11, the portions SSA, 55B and 55C of the workpiece 41 supportedlon the female die shoulder edges 36.2 and 37.1 movehorizontally and vertically toward the nose of the male die to contactthe shoulders at different lines of contact, as 57A, 57B and 57C,respectively along planes 155A, 1558 and 155C, respectively.

The forces of the impact of the downward motion of the male die, 86 and87, on the shoulders 36 and 37 of the female or base die 31 is met bythe supporting upward center force 88-along the tail of the female dieand a tensile force 89 is directed horizontally across the body of thefemale die below the apex 39 of the female die groove or notch 38: thehigh thermal conductivity of the aluminum alloy 7178 permits, by rapidquenching of the extruded female die as herein provided, a broad band ofhigh tensile strength material (indicated by the high hardnessmeasurement) below the surfaces 38.1, 38.2 and apex 39 to resist tensilestresses applied thereto without stress concentration as might causefatigue failure. The band is at least A inch wide.

In operation the surface temperature of sheet 41 of 3/64inch -3l16 inchsteel stock rises only to 125l35 F. (which is well below the transitiontemperature of the alloy used) along line of contact of the shoulders 36and 37 and the work piece (lines 56 and 57 in FIG. 9) during operationof brake presd due as 60 with dies at room temperature of 6080 F.

While the 7l78-T-6 alloy is preferred another alloy composition whichmay be used herein, and is known as 7075-T-6; it has the followingcharacteristics and composition:

Modulus of elasticity l0.3 X 10' p.s.i Tensile strength 81,000 p.s.i.Yield strength 72,000 p.s.i. Elongation, I: in 2 in. 14.0 BrinellHardness I60 Component 1: by Weight it]. Remainder In the operation ofdeforming, shown in FIGS. 8, 9 and 10, the workpiece 41 is struck on theupper surface 42 thereof with the vertically downwardly moving nose 17of the punch 11, which has a large modulus of resilience (about 300 in.lbs. per cu. in. Concurrently, lower surface 44 of piece 41 is supportedon unit 31 shoulders at zones 56 and 57, spaced apart along directionand distance between edges 36.1 and 37.1 transverse to direction ofmovement of nose 17. Zones 56 and 57 are indicated by points on FIG. 9because these zones are so thin as to be lines.

The mass of the ram 66 of the press 60 to which the punch die 11 isattached drives the punch die 11 toward and downwardly into groove 38downward forcefully and rapidly. The force thereof (86 and 87) isinitially met, as in FIG. 8, when the nose 17 first contacts uppersurface 42, by a combination of tensile forces parallel to surfaces 38.2and 38.1 and compressive forces opposite 86 and 87 perpendicular to topshoulder surfaces. As the punch moves further downward as shown in FIG.9, the elastic limit of the sheet 41 is exceeded, the plane of thebottom surface 44 moves adjacent each shoulder, 36 and 37, as shown for37, from surface 137.3 (an extension of surface 37.3) to plane A toplane 1558 to 155C. As the increments 55A, 55B and 55C of work piece 41successively move centrally of the shoulder edges 36.2 and 37.1 as shownfor shoulder edge 37.1, (a) the angle to thehorizontal of planes 155A,1558 and 155C, respectively, of the bottom surfaces 57A, 57B and 57C ofplate 41 portions 55A, 55B and 55C contacting each shoulder surface, as37, increase, and (b) the lateral component of force applied to theshoulders, as 36 and 37, accordingly increase from (i) the direction ofa force, as 87, normal to the surface 37.3 (the top of shoulder 37) andparallel to a line, as 137.3 normal to surface 37.3 to (ii) directions255A, 255B and 255C which have increasing horizontal components.

A yielding base die, as 31, with a low (about 10.4 X 10 p.s.i.) modulusof elasticity provides a lesser initial force of the die 11 againstplate 41 and of plate 41 against die 31 than does a steel die, (ofgreater modulus of elasticity; i.e., 30 X 10 p.s.i.) because it takesabout three times as long for the vertical displacement of the plate todevelop against the alloy die as against a steel die; hence, the initialshock or impact of the ram is proportionately substantially decreased,although the tensile strength across the die 31 is adequate to maintainits dimensional stability and permit rapid punching action; e.g., one tothree strokes per second without thermal or mechanical damage. The wearand fatigue resistance of the dies, as 31, 11 and 21 are accordingly fargreater than provided by steel dies of comparable modulus of resilienceor surface hardness. The strain suffered by nose 17 and shoulders 36 and37 equals the square root of the quotient of:

a. square of stress applied (which stress equals elastic strengthdivided by strain) divided by:

b. twice the product of:

i. modulus of elasticity of the alloy, times ii. modulus of resilienceof the alloy.

. Additionally, the extensibility (low value of E) alloy used for die 31allows a progressive yet elastic lateral displacement of the faces 38.1and 38.2 during movement of the nose 17 towards apex 39 and reduces thefrictional drag between the centrally moving increments of surfaces as55A, 55B and 55C of the bottom surface 44 and the shoulder edges 36.2and 37.1. Accordingly, the yieldability of the alloy of die 31 limitsstretching of the work piece 41 between (a) the nose as 17 and (b) thezones or lines of contact of the sheet 41 and shoulders 36 and 37 and soavoids hardening and/or rupture of the work piece 41.

Another application of the process of deforming metal herein disclosedis in the operation of an extrusion press, as shown in FIG. 11, where anextrusion punch die 91 with a lower face 97 and cylindrical side face 96operates to deform a steel sheet 94. The body of the die 91 is made of7178-T-6 alloy with a bottom surface hardness of 38 Rockwell C andhardened, as 11, to a depth of 16 inch. The interior of the die 91 wouldhave a hardness of about 6 Rockwell C. The female die 93 would have ahardness of 38 Rockwell C at the edge of its circular shoulder 99, andhave a 34 Rockwell C hardness and comparable tensile strength in a band6 inch deep around the perimeter of the die orifice 98 to achieve theblunting of the die impact while providing the needed tensile strengthand energy absorption characteristics above-described for dies 11 and31.

The hammer head 85 shown in FIG. 12 is another example of an impactapplying tool within the scope'of this invention which is made of alloyas used in FIG. 1 and is particularly used for removing dents from steelautomobile fenders. Such tool 85 would have a hardness at its head 84,of 28 to 48 Rockwell C to a depth of is inch and an interior hardnessbetween 4 and 6 Rockwell C.

The combination 130 of a piston connecting rod 131 with pin 141 and apiston 140 as shown in FIG. 13 is also included within the scope of thisinvention. The piston 140 is cylindrically shaped as conventionally usedin a water cooled automotive engine and includes a piston pin or wristpin, 141, which pin is a solid cylinder supported at its ends on bossessupported on walls of the piston. The hardness of the bearing surface139 of the connecting rod 131 at its upper or wrist pin end in contactwith and adjacent the piston pin 141 is formed in range of 28-48Rockwell C by procedure above described and the bearing surface 142thereof to be in contact with the crankshaft 143 is also formed in rangeof 28 to 48 Rockwell C by the same procedure.

Connecting rod 131 is formed of the 7178-T-6 alloy hereinabove describedand is heat treated to provide hardness in its core 138 in range of 6 to8 Rockwell C and, as in the dies 11, 21 and 31 herein described, has amodulus of resilience of about 300 in.-lbs. per cubic inch.

The piston pin 141 is made of the same alloy and is heated to have thesame hardness at its bearing surface adjacent 139 and in its core, andalso has a modulus of resilience of about 300 in.-lbs. per cubic inch,as does the connecting rod 131.

TABLE I1 Rockwell C I-IARDNESS (a) Taken on Hardness Measurements (b) wPiece No. Surface Core Nose Depth 11 (d) 9((101) 6(104) 48(107) 8(108)-(6) 12(102) 4(105) 28(111) 9(109) 31 (d) 19(103) 17(106) 38(112)32(110) (a) Data taken with Clark Hardness Tester. Rockwell C. Bralediamond penetrator. major load Kg.; tester described in United StatesPatents 2.319.208and 2.326.759.

(b)Measurements taken at points and surfaces indicated in parenthesis atpositions as on each ofFlGS. 1, 2 and 3. Item 41 is a 3/64 thick steelsheet for dies 11 and 31.

(c) Piece tested was anodically coated as described in text herein tothickness of two mils; items 11 and 31 tested as in this table were notcoated. for purpose of comparison. although such is usual treatment. (d)Impact tests have been run. and where steel dies split, the dies as 11and 31 made according to this invention survived.

321p of nose to line 13.1-13.2 and/or line between edges 14.3 and TABLEIV Dimensions of Embodiment No. 31. Edge to edge notation Distance(inches) 23.4-23.2 (horiz. dist.) 1.50 24.1-24.2 .5 24.2-24.4 .625 22.3.125"R 23.1 .188"R 23.6 .438"R 22.4 .312"R 23.4-24.3 (vertL) .50 24.3-273.750 23.4-26.1 1.812 26.1-26.3 0.50 27 .062"R 28.2(width) 28.1283 .312"

TABLE IV Dimensions of embodiment 31 and the like Embodiment 31' No. 31Edge to edge distance Measurements in inches 34.3-34.4 .50 .50 34.1-34.3.625 .625 34.1-37- 2.250" 1.75 surface 36.1321 to 2.0 1.25 surface37.1-32.2 37.1-36.1 1.50" .625 37.1 .031" .125 38.1,ang1e to horiz. 4544 39 .063"R .02R 32.1 .375R .03R 36.1 .12$"R .125R

1 claim:

1. Process of repeatedly deforming successive portions of metal sheet bystriking one surface of work of such portions with semi-rigid resilientmember at one zone in one direction while supporting the sheet on acompression member on a surface of said sheet opposite tosaid onesurface at zones spaced apart from the said first zone along a directiontransverse to said one direction and deforming the sheet while applyingstress to said compression member according to the formula:

\I F {(2 x E x M) where A= FIE 5. Process as in claim 4 wherein saidmetal sheet is a steel sheet.

6. Process as in claim 5 wherein said member is an integral impactapplying tool with a surface hardness of 160 Brinell and is composed ofan alloy of the folling composition:

Component '1: by Weight Mn 30 Si 40 Fe .50 cu Range of l.6 2.4 Mg Rangeof 2.44.] Cr Range of .l8-.35 Zn Range of 6.3-7.3

al. Remainder 7. An integral impact applying tool with a surfacehardness of Brinell and a modulus of resilience of at least 300 inchpounds per cubic inch and a modulus of elasticity of about 10.4 X 10'p.s.i.

8. Apparatus as in claim 7 comprising a brake press punch with a maximumhardness at its nose and a lesser hardness at other points on itssurface and a lesser hardness internally, the hardness at the noseextending to a depth of 56 inch.

9. Apparatus as in claim 8 in combination with a female die having 2spaced apart shoulders and a groove therebetween, and said groove,surface and shoulders having a like hardness and resilience to a depthof at least inch.

10. Apparatus as in claim 9 composed of an alloy of the followingcomposition Tensile strength p.s.i. 81900-88000 Yield strength 7 lDUO-78,000 Elongation k in 2 in. 10 Shear strength, p.s.i. 49000-52000Modulus of elasticity 10.4 10' Surface hardness (500 kg. load 160 H) mm.Bail) Thennal conductivity .57 cal/sq. e-Je-JleeJ" C ("2.7 BTU/sq.fL/hrJflJ'F. Component k by Weight Range of 1.6-2.4 8 Range of 2.4-3.1Cr Range of.l8 .35 Zn Range of 6.3-7.3 al. Remainder

1. Process of repeatedly deforming successive portions of metal sheet bystriking one surface of work of such portions with semirigid resilientmember at one zone in one direction while supporting the sheet on acompression member on a surface of said sheet opposite to said onesurface at zones spaced apart from the said first zone along a directiontransverse to said one direction and deforming the sheet while applyingstress to said compression member according to the formula: Delta > OR =square root i F2 /(2 X E X M) where E stress in p.s.i. applied bystriking. E modulus of elasticity M modulus of resilience Delta strain,and wherein M at least 300 in.-lb./cu. in.
 1. Process of repeatedlydeforming successive portions of metal sheet by striking one surface ofwork of such portions with semi-rigid resilient member at one zone inone direction while supporting the sheet on a compression member on asurface of said sheet opposite to said one surface at zones spaced apartfrom the said first zone along a direction transverse to said onedirection and deforming the sheet while applying stress to saidcompression member according to the formula: Delta > or = Square Root iF2 /(2 X E X M) where E stress in p.s.i. applied by striking. E modulusof elasticity M modulus of resilience Delta strain, and wherein M atleast 300 in.-lb./cu. in.
 2. Process as in claim 1 wherein E equalsabout 10.4 X 106 p.s.i.
 3. Process as in claim 2 wherein M equal
 300. 4.Process as in claim 2 wherein Delta F/E
 5. Process as in claim 4 whereinsaid metal sheet is a steel sheet.
 6. Process as in claim 5 wherein saidmember is an integral impact applying tool with a surface hardness of160 Brinell and is composed of an alloy of the folling composition:Component % by Weight Mn 30 Si 40 Fe .50 cu Range of 1.6-2.4 Mg Range of2.4-3.1 Cr Range of .18-.35 Zn Range of 6.3-7.3 al. Remainder
 7. Anintegral impact applying tool with a surface hardness of 160 Brinell anda modulus of resilience of at least 300 inch pounds per cubic inch and amodulus of elasticity of about 10.4 X 106 p.s.i.
 8. Apparatus as inclaim 7 comprising a brake press punch with a maximum hardness at itsnose and a lesser hardness at other points on its surface and a lesserhardness internally, the hardness at the nose extending to a depth of1/8 inch.
 9. Apparatus as in claim 8 in combination with a female diehaving 2 spaced apart shoulders and a groove therebetween, and saidgroove, surface and shoulders having a like hardness and resilience to adepth of at least 1/8 inch.